Most rotorcraft have a natural harmonic, Bell H1 Huey's were notorious for a 1:1 harmonic thump that shook the hell out of things. Most crew chiefs were able to reduce the vibration to a minimum, but and out of phase rotor balance would shake it apart. That aid I have no idea what natural harmonic an Inspire has, but I recon that 4 two blades props creates an unusual phenomena, and when you yaw the aircraft it could easily exacerbate the affect.

Good advice, however, the standard DJI props (for the P series as well) are almost perfect. At least, none of my blades ever needed extreme balancing. I could improve just so little.
It shouldn't be that of an issue with original blades and smooth running motors.